Question

When ultraviolet light of wavelength 100 nm is incident upon a sample of silver metal, a potential difference of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. The potential required to stop photo electrons when light of wavelength 200 nm is incident upon silver is ______.

Options

• 1.5 V

• 1.85 V

• 1.95 V

• 2.37 V

Answer 1

When ultraviolet light of wavelength 100 nm is incident upon a sample of silver metal, a potential difference of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. The potential required to stop photo electrons when light of wavelength 200 nm is incident upon silver is 1.5 V.

Explanation:

Given,

`Phi = 4.7` eV

for λ = 100 nm, V_s = 7.7 volt

for λ = 200 nm

V_s = ?

`eV_s = (ch)/lambda - Phi`

= `(3 xx 10^8 xx 6.62 xx 10^-34)/(2 xx 10^-7 xx 1.6 xx 10^-19) - 4.7`

= 6.2 – 4.7 = 1.5 V

⇒ V_s = 1.5 volt